1. Field of the Invention
The present invention relates to a neighbor discovery mechanism in a heterogeneous network environment. More particularly, the present invention relates to a neighbor discovery method and apparatus that is capable of performing a network-transparent neighbor discovery procedure in a heterogeneous network environment.
2. Description of the Related Art
With advances in technologies and the advent of various Internet services, the number of Internet Protocol (IP) networks and network users have increased dramatically. The increase in the number of networks and devices accessing the networks cause various problems such as an exhaustion of IP addresses (i.e., the 32-bit IP version 4 (IPv4) addresses), an increase in network complexity, a service delay, a reduced level of security and an insufficient degree of compatibility with new technologies. IP version 6 (IPv6) has been proposed for addressing such shortcomings in the conventional IPv4.
IPv6 is a 128-bits addressing system that addresses the address exhaustion problem of IPv4. In addition to the advantage of larger address space, IPv6 has features such as Neighbor Discovery (ND), Router Discovery (RD), Stateless Address Autoconfiguration, Dynamic Host Configuration Protocol version 6 (DHCPv6), Maximum Transport Unit (MTU) discovery, etc. Here, the ND protocol is implemented for recovering a neighbor node (host or router), and the RD protocol is implemented to discover routers on the local link to which the host is connected. The Stateless Address Autoconfiguration allows a node to configure itself with a globally unique IPv6 address, and the DHCPv6 is used to statefully assign IP addresses and other networking information to the nodes. The MTU discovery is used for determining a maximum transmission unit size on the network path between two nodes to avoid IP fragmentation.
In the meantime, in order for a mobile node to roam across heterogeneous networks while maintaining a certain Quality of Service (QoS), an intelligent handover technique is required. Media Independent Handover (MIH) is a standard being developed by the Institute of Electrical and Electronics Engineer (IEEE) 802.21 to enable the handover of IP sessions and it supports IPv6.
However, the ND function, as a key feature of the IPv6, specified in the current IEEE 802.21 specification is insufficient for implementation in all the types of heterogeneous environment scenarios. This is because the different technology networks perform the neighbor discovery in different manners. For example, the IEEE 802.3 and 802.11 networks operate with Media Access Control (MAC) based routing protocols, while the IEEE 802.16 networks use a tunneling technique with a Connection Identifier (CID) rather than a MAC address. Accordingly, there is a need to develop a neighbor discovery technique that enables the MIH to operate in a manner that is transparent to network interfaces.